The sister of Eddie Ray Routh, the Marine reservist accused of murdering former Navy SEAL Chris Kyle and another man at a rural Texas gun range, told police she was "terrified for her life" when her brother showed up at her house and allegedly told her what he'd done.

In a tape of the 911 call Laura Blevins made to the Midlothian Police Department Saturday evening, her voice quivers and shakes as she says Routh showed up at her home in a pickup truck she had never seen before.

"He told me that he has committed a murder," she said. "And I am terrified for my life ... Because I don't know if he's going to come back here.

"Now, listen ... I don't know if he's being honest with me," she said. "I'm just really terrified."

The 911 operator suggested that Blevins and her family come to the police station, which was nearby, and told her to stay on the phone as they made the trip.

"OK, that would be great because I'm really scared," Blevins said.

When the 911 operator asked Blevins whether Routh told her who he had killed, she said: "He said he killed two guys; they went out to a shooting range. Like he's all crazy. He's f---ing psychotic. I'm sorry for my language. I don't know if he's on drugs or not."

As they were on their way to the police station, Blevins gave the phone to her husband, who described the pickup truck Routh was driving, and said that there were two guns in the truck

"He was talking ... kind of ... babble," "He's recently diagnosed with PTSD ... Post Traumatic Stress Disorder ... and he's been acting a little weird from that. He just got out of the mental hospital, actually."

Blevins husband said Routh had been released from Green Oaks Psychiatric Hospital "about a week ago."

According to police records obtained by the Dallas Morning News, Routh had been confined to Green Oaks twice since September.

Routh, 25, is accused of shooting Kyle, 38, who served four tours of duty in Iraq and wrote the best-selling memoir "American Sniper." He also allegedly shot another veteran, Chad Littlefield, 35, when the three men were at a gun range in Erath County, Texas, on Saturday.

Guards at the Erath County Jail used a Taser on Routh on Sunday night, after he became belligerent and refused to give jailers the tray on which he had been served dinner, authorities said.

When guards came to collect his tray, Routh "was trying to attack them," said Erath County Sheriff Tommy Bryant at a press conference.

An official at the county jail, unauthorized to speak for attribution, told ABCNews.com that Routh had been placed on suicide watch and was confined to a solitary cell, restrained in a chair.

Routh was arrested Saturday, after the men's bodies were found. Police chased down Routh, who was driving Kyle's stolen pickup truck, disabling the vehicle with tacks and arresting the suspect.

Police said Sunday that Kyle and Littlefield were both killed at close range using a semi-automatic pistol.

Routh was charged with two counts of capital murder and his bond was set at $3 million.

He offered no confession or hint at a motive, police said.

Routh will be appointed an attorney, and will likely receive a lawyer experienced in handling capital cases.

Kyle founded FITCO, an organization that encouraged veterans to cope with post-traumatic stress through exercise. Police have not yet confirmed that Routh was diagnosed with PTSD.